The present invention relates to an ultrasonic wave motor and, more specifically to an ultrasonic wave motor device in which, in accordance with a result of measuring a characteristic of an ultrasonic wave motor driving circuit or the ultrasonic wave motor device and analyzing the measured value, the driving circuit is corrected and the characteristic (stability, environmental reliability) is improved.
Conventionally, for example, as disclosed in Japanese Unexamined Patent Publication No. JP-A-62-92781, an ultrasonic wave motor driving circuit includes by a variable oscillating body, a 90u phase shifter, two power amplifiers, a current detector, and a voltage detector, a controlling circuit. The ultrasonic wave motor undergoes a change in a resonance frequency in respect to a change in temperature, load, power supply voltage or the like and, therefore, suffers from the problem in which a driving circuit per se is very complicated and large-sized.
In order to resolve the problem, there has been made a proposal as disclosed in, for example, Japanese Unexamined Patent Publication No. JP-A-8-107686 in which a driving circuit is constituted by a self-excited oscillation circuit comprising an amplifying circuit, a phase setting circuit and an ultrasonic wave motor having a piezo-electric body by which a total of the driving circuit is simplified and downsized.
However, according to a driving circuit as disclosed in Japanese Unexamined Patent Publication No. JP-A-8-107686, although a value of an element in respect of phase setting is determined based on a theoretical calculation, the problem of possibility of causing a difference in characteristics among respective products caused by a dispersion in characteristics of respective elements used in the ultrasonic wave motor driving circuit, a dispersion in the characteristic of the ultrasonic wave motor per se or the like, cannot be disregarded.
It is an object of the present invention to provide an ultrasonic wave motor device promoting characteristics (stability, environmental reliability) by simply enabling to correct the difference in the characteristic among the respective products in actual steps of fabricating the ultrasonic wave motor.